Thermal Phase Behavior of DMPG as revealed by 2H- and 31P- NMR

Loew, C. and Riske, K. A. and Lamy, M. T. and Seelig, J.. (2011) Thermal Phase Behavior of DMPG as revealed by 2H- and 31P- NMR. Langmuir, 27 (16). pp. 10041-10049.

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Official URL: http://edoc.unibas.ch/dok/A5844181

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The synthetic lipid 1,2-dimyristoyl-sn-3-phosphoglycerol (DMPG), when dispersed in water/NaCl exhibits a complex phase behavior caused by its almost unlimited swelling in excess water. Using deuterium (2H)- and phosphorus (31P)-NMR we have studied the molecular properties of DMPG/water/NaCl dispersions as a function of lipid and NaCl concentration. We have measured the order profile of the hydrophobic part of the lipid bilayer with deuterated DMPG while the orientation of the phosphoglycerol headgroup was deduced from the 31P-NMR chemical shielding anisotropy. At temperatures <30 degrees C we observe well-resolved 2H- and 31P-NMR spectra not much different from other liquid crystalline bilayers. From the order profiles it is possible to deduce the average length of the flexible fatty acyl chain. Unusual spectra are obtained in the temperature interval of 20 degrees C to 25 degrees C, indicating one or several phase transitions. The most dramatic changes are seen at low lipid concentration and low ionic strength. Under these conditions and at 25 degrees C the phosphoglycerol headgroup rotates into the hydrocarbon layer and the hydrocarbon chains show larger flexing motions than at higher temperatures. The orientation of the phosphoglycerol headgroup depends on the bilayer surface charge and correlates with the degree of dissociation of DMPG-Na+. The larger the negative surface charge the more rotates the headgroup towards the non-polar region.
Faculties and Departments:05 Faculty of Science > Departement Biozentrum > Former Organization Units Biozentrum > Biophysical Chemistry (Seelig J)
UniBasel Contributors:Seelig, Joachim
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:American Chemical Society
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:14 Nov 2017 12:56
Deposited On:14 Sep 2012 06:41

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